The broad concept of gear wrenches, that is, wrenches including a ring gear meshing with a pinion gear to drive a tool such as a screw driver or drill, is known. Such wrenches are disclosed, for example, in U.S. Pat. Nos. 732,108 and 2,756,792. These wrenches are designed to produce a desired input to output ratio; that is, rotation of the operating handle results in desired rotation of the tool. In using the tool for some applications, it is desirable to have a relatively fast output; therefore, the wrench is designed to have, for instance, a 1:3 ratio. In other applications, it is desirable to have a relatively slow output; therefore, the tool is designed to have, for instance, a 3:1 ratio.
Heretofore, it was necessary for the worker or operator to carry a plurality of gear wrenches, each having the desired input-output ratio. After considerable research and experimentation, the gear wrench of the present invention has been devised to provide multiple input ratios such as 1:3, 3:1 and 1:1, whereby the worker is only required to carry one gear wrench for multiple applications.
The manually operated gear wrench of the present invention comprises, essentially, a fixed hand plate and a wrench plate rotatably mounted thereon. The wrench plate carries a ring gear which meshes with a pinion gear rotatably mounted on the hand plate. Studs adapted to selectively receive socket handles and tools are connected to the pinion gear and wrench plate. By connecting an operating handle to the pinion stud and a tool to the wrench plate stud an input to output ratio of approximately 3:1 is obtained. By connecting the operating handle to the wrench plate stud and the socketed tool to the pinion stud an input to output ratio of approximately 1:3 is obtained. A releasable locking mechanism is provided between the fixed hand plate and pinion gear to prevent relative rotation therebetween, to thereby provide an input to output ratio of 1:1. Further, the locking mechanism, when placed in a neutral disengaged position, allows a 1:1 ratio to result when the user grasps a hand grip portion on the wrench plate.
The operating handle can be either a crank or a hand knob containing a ratchet mechanism. It is contemplated that various tools, such as drills, screw drivers, socket wrenches, Allen wrenches, and the like, can be employed.